The pleural cavity of a mammal is the body cavity that surrounds the lungs. The pleura is a serous membrane which folds back upon itself to form a two-layered, membrane structure. The thin space between the two pleural layers is known as the pleural cavity.
The outer pleura (parietal pleura) is attached to the chest wall. The inner pleura (visceral pleura) covers the lungs and adjoining structures, including blood vessels, bronchi and nerves.
The pleural cavity, with its associated pleurae, aids optimal functioning of the lungs during respiration. The pleural cavity contains pleural fluid, which allows the pleurae to slide effortlessly against each other during ventilation.
Pleural fluid is a serous fluid produced by the normal pleurae. Most pleural fluid is produced by the parietal circulation (intercostal arteries) and reabsorbed by the lymphatic system. Thus, pleural fluid is produced and reabsorbed continuously under normal physiological conditions.
Individuals experiencing e.g. a pleural effusion (accumulation of fluid in the pleural cavity), hemothorax (accumulation of blood in the pleural cavity), pneumothorax (collapsed lung), or empyema (accumulation of pus in the pleural cavity) often require surgery in the form of insertion of a chest tube into the pleural cavity to provide relief from and/or to treat the observed symptoms.
In case of hydrothorax, hemothorax or chylothorax, the ideal location of the tip of the chest tube is close to the diaphragm, posteriorly in the pleural cavity, since this is the lowest point of the cavity. In case of pneumothorax, the ideal location of the tip of a chest tube is in the cranial, anterior part of the pleural cavity because air tends to be located at the top of the cavity. In case of empyema, the ideal location is into the empyema cavity which can vary in location from patient to patient.
It is absolutely essential that a chest tube is always placed at the intended location of a body cavity. A misplaced chest tube may lead to impaired function which may cause severe discomfort for the patient and furthermore result in an extended hospital admission. A prolonged period of chest tube insertion increases the risk of infection through the chest tube passage. In some cases it is necessary to replace an inserted chest tube and to insert a new chest tube due to an improper and incorrect location of the initially inserted chest tube.
The typical symptoms of pneumonia (lung infection) include fever, cough, and sputum discharge, shortness of breath and chest pain. Pneumonia can progress with parapneumonic effusion and 1-5% of the patients develop pus in the pleural cavity (empyema). This type of lung infection can progress to systemic disease with such signs as weakness, and loss of appetite (anorexia). Chest x rays can allow the clinician to view the pleural effusion or empyema and can also help to detect pneumothorax, since there is visual proof in the displacement of the tissues covering the lungs as a result of air in the pleural cavity. Additionally, during physical examinations, people with pneumothorax have diminished breath sounds, hyperesonance on percussion (a highly resonating sound when the physician taps gently on a patient's back), and diminished ability to expand the chest.
Chest tubes are well known in the art and exist in various shapes and forms, including “straight” as well as “angular” configurations. Chest tubes can be manufactured in rigid as well as flexible polymeric materials and various procedures exist for their insertion into a body cavity.
WO 2006/019783 (Medical Components, Inc.) discloses a catheter tunnelling device integrally connected at one end thereof to a trocar by means of a slidable adapter that facilitates a physical connection between the trocar and the catheter. WO 2006/019783 does not address the problem of how to accurately position a catheter in a body cavity, such as the pleural cavity. Also, use of a trocar is mandatory when operating the catheter tunnelling device. The present invention does not employ a trocar physically connected to a catheter or chest tube.
U.S. Pat. No. 5,509,909 (Moy) discloses a bent chest tube assembly capable of being straightened by a trocar located internally in the chest tube. Once the trocar is retracted from the lumen of the chest tube, the chest tube returns to its pre-formed and fixed, angular shape (angle of approx. 90 degrees). It is disclosed that the bent, distal portion of the chest tube provides an anchoring function and reduces the likelihood of inadvertent removal of the catheter from the pleural cavity. U.S. Pat. No. 5,509,909 does not address the problem of how to accurately position a catheter in a body cavity. Use of a trocar is mandatory when inserting a chest tube in a body cavity according to the method disclosed in U.S. Pat. No. 5,509,909. Also, the present invention does not require or depend on the use of a trocar for directing the insertion of a catheter or chest tube into e.g. a pleural cavity of an individual.
P2005-341987A (Unknown assignee) discloses a curved, trocar guide used for inserting a catheter into a body cavity. P2005-341987A does not address the problem of how to accurately position a catheter in a body cavity, such a the pleural cavity. Use of a trocar is mandatory when inserting a chest tube according to the method disclosed in P2005-341987A. Also, the present invention does not require or depend on the use of a trocar for directing the insertion of a catheter or chest tube into e.g. a pleural cavity of an individual.
U.S. Pat. No. 6,849,061 (Wagner) discloses a bent catheter having a generally, L-shaped form. The catheter material is sufficiently rigid to maintain the distal section of the catheter in a correct position, but flexible enough to move when displaced to prevent further injury to the individual being treated. U.S. Pat. No. 6,849,061 does not address the problem of how to accurately position a catheter in an intended position in a body cavity, such as the pleural cavity of an individual.
U.S. Pat. No. 4,813,929 (Semrad) discloses a method in which a guide wire is inserted into a pleural cavity through a bore needle. A pleural access catheter is delivered to the pleural cavity over the guide wire and a chest tube is subsequently diverted into the pleural cavity through the access catheter. U.S. Pat. No. 4,813,929 does not address the problem of how to accurately position a catheter in an intended position in a body cavity, such as the pleural cavity. Use of a guide wire is mandatory when inserting a chest tube into a pleural cavity according to the method disclosed in U.S. Pat. No. 4,813,929. Also, the present invention does not require or depend on the use of a guide wire for directing the insertion of a chest tube into e.g. the pleural cavity of an individual.
Use of a trocar is mandatory when using the methods and devices disclosed in WO 2006/019783, U.S. Pat. No. 5,509,909 and P2005-341987A (cf. above). However, the art teaches away from using a trocar for chest tube insertions because of the dangers associated with using a trocar. For example, Klopp et al. states in Dtsch. Med. Wochenschr., 2009, vol. 134(11): pp. 536-9 [PMID: 19235680], that insertion of a chest tube aided by using a trocar frequently results in severe complications such as hemothorax, dislocation, lung lacerations, and injury to organs in the thoracic or abdominal cavity.
As taught in U.S. Pat. No. 4,813,929A (cf. above), a pleural access catheter can be delivered to the pleural cavity over a guide wire and a chest tube can subsequently be diverted into the pleural cavity through an access catheter. While guide wires generally improve the ability to position correctly a chest tube in the pleural cavity of an individual, recent evidence, cf. herein below, suggests that even a guide wire assisted insertion of a chest tube into the pleural cavity does not in all cases result in the correct positioning of the chest tube.
Protic et al. (2009) reported in Eur. J. Emerg. Med. [PMID: 19704377] success rates of a tube thoracostomy study using i) a targeted, wire-guided (TWG) procedure against ii) a classical surgical (CS) procedure. The TWG and CS groups were each divided into four subgroups according to the intended target position of the chest tube in the pleural cavity: back-down-right, front-up-right, front-up-left and back-down-left, respectively. The placement of the chest tube was marked successful if the tip of the chest tube was located at the intended position. The success rate with the TWG procedure was 79%, whereas the success rate with the CS procedure was as low as only 30%.
In summary, it can be concluded that trocars are less safe to use when inserting a chest tube into a pleural cavity. Also, a classical surgical procedure, wherein no directional guidance to aid the correct positioning of a chest tube in the pleural cavity is employed, results in a failure to position a chest tube correctly at the intended position in the pleural cavity in 2 out of 3 patients (cf. 30% success rate, as cited by Protic (2009) herein above).
Although guide wire assisted insertions of chest tubes into the pleural cavity do provide an improved success rate over the classical surgical procedure (cf. above), 1 in 5 patients can nevertheless—based on the study reported by Protic (2009) herein above—be expected to be subjected to unpleasant, inconvenient and unnecessary further surgical steps as a consequence of having had a chest tube incorrectly positioned in the pleural cavity.
Accordingly, there is a need for a simple, inexpensive and safe method for inserting and accurately positioning a chest tube at an intended position in a body cavity, such as e.g. the pleural cavity of an individual.
The unnecessary and additional health care costs associated with a chest tube replacement and an extended hospital admission, the increased risk to a patient of contracting an infection and the pain and general inconvenience caused by the replacement of an incorrectly positioned chest tube can be avoided by using the chest tube guiding device according to the present invention.